The instant invention relates to a document feeding device, and more particularly to a device which enables an operator of a document feeding machine to control the pack pressure for various types and sizes of materials being fed from the document feeder.
Inserting machines typically include a plurality of feeding devices which feed documents from a pack of documents situated in a hopper seriatim to a transport deck therebelow, from which a collated packet of documents are eventually inserted into an envelope. The inserter document feeders employ hoppers that generally are inclined at a fixed angle which usually is somewhere between about 20 and 30 degrees. The feeder depends on gravity to slide the documents down to and against a separator roller and stone. The nature of this system is such that it is virtually impossible to maintain an ideal pack pressure and pack angle in the documents throughout the hopper's full capacity. A full hopper creates too high a pack pressure and angle while a near empty hopper creates too low a pack pressure and angle. The nature of the material being fed may also contribute to the difficulty of maintaining the optimum pack pressure and angle depending upon whether the material is glossy or rough (finish), or whether it is curled, twisted, spongy, thick or heavy.
If the pack pressure is very low, insufficient force will be generated and no documents will be fed from the hopper. The addition of more documents remedies this problem. However, when operating large inserting machines, with multiple document feeders, it is in the interest of the operator to load each hopper to capacity, thereby necessitating less frequent reloading. In many cases, especially with heavier documents such as booklets, the pack pressure then becomes excessive, and the pack pressure causes the frictional force between documents to become greater than the resistive force of the retarding element, typically the supporting surface of the hopper, causing double documents to be fed. As the gap of the separator device will not allow doubles, the feed roller "peels" the top pages of multiple sheet documents, thereby causing a jam.
The instant invention alleviates the foregoing condition and allows the operator to fully load the feeder hopper by maintaining a constant pack pressure within the desirable range.